mmc: sdhi: Add write16_hook

Some controllers require waiting for the bus to become idle
before writing to some registers. I have implemented this
by adding a hook to sd_ctrl_write16() and implementing
a hook for SDHI which waits for the bus to become idle.

Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Magnus Damm <magnus.damm@gmail.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Chris Ball <cjb@laptop.org>

2 files changed, 41 insertions, 0 deletions

diff --git a/drivers/mmc/host/sh_mobile_sdhi.c b/drivers/mmc/host/sh_mobile_sdhi.c
index ce500f03df85..774f6439d7ce 100644
--- a/drivers/mmc/host/sh_mobile_sdhi.c
+++ b/drivers/mmc/host/sh_mobile_sdhi.c
@@ -26,6 +26,7 @@
 #include <linux/mmc/sh_mobile_sdhi.h>
 #include <linux/mfd/tmio.h>
 #include <linux/sh_dma.h>
+#include <linux/delay.h>
 
 #include "tmio_mmc.h"
 
@@ -55,6 +56,39 @@ static int sh_mobile_sdhi_get_cd(struct platform_device *pdev)
                 return -ENOSYS;
 }
 
+static int sh_mobile_sdhi_wait_idle(struct tmio_mmc_host *host)
+{
+        int timeout = 1000;
+
+        while (--timeout && !(sd_ctrl_read16(host, CTL_STATUS2) & (1 << 13)))
+                udelay(1);
+
+        if (!timeout) {
+                dev_warn(host->pdata->dev, "timeout waiting for SD bus idle\n");
+                return -EBUSY;
+        }
+
+        return 0;
+}
+
+static int sh_mobile_sdhi_write16_hook(struct tmio_mmc_host *host, int addr)
+{
+        switch (addr)
+        {
+        case CTL_SD_CMD:
+        case CTL_STOP_INTERNAL_ACTION:
+        case CTL_XFER_BLK_COUNT:
+        case CTL_SD_CARD_CLK_CTL:
+        case CTL_SD_XFER_LEN:
+        case CTL_SD_MEM_CARD_OPT:
+        case CTL_TRANSACTION_CTL:
+        case CTL_DMA_ENABLE:
+                return sh_mobile_sdhi_wait_idle(host);
+        }
+
+        return 0;
+}
+
 static int __devinit sh_mobile_sdhi_probe(struct platform_device *pdev)
 {
         struct sh_mobile_sdhi *priv;
@@ -86,6 +120,8 @@ static int __devinit sh_mobile_sdhi_probe(struct platform_device *pdev)
         mmc_data->hclk = clk_get_rate(priv->clk);
         mmc_data->set_pwr = sh_mobile_sdhi_set_pwr;
         mmc_data->get_cd = sh_mobile_sdhi_get_cd;
+        if (mmc_data->flags & TMIO_MMC_HAS_IDLE_WAIT)
+                mmc_data->write16_hook = sh_mobile_sdhi_write16_hook;
         mmc_data->capabilities = MMC_CAP_MMC_HIGHSPEED;
         if (p) {
                 mmc_data->flags = p->tmio_flags;
diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index 0c22df0f954d..211ef6e7a820 100644
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -153,6 +153,11 @@ static inline u32 sd_ctrl_read32(struct tmio_mmc_host *host, int addr)
 
 static inline void sd_ctrl_write16(struct tmio_mmc_host *host, int addr, u16 val)
 {
+        /* If there is a hook and it returns non-zero then there
+         * is an error and the write should be skipped
+         */
+        if (host->pdata->write16_hook && host->pdata->write16_hook(host, addr))
+                return;
         writew(val, host->ctl + (addr << host->bus_shift));
 }